/*eslint-disable  max-depth */
(function() {
  'use strict';
  function pixelAt(idata, x, y) {
    var idx = (y * idata.width + x) * 4;
    var d = [];
    d.push(
      idata.data[idx++],
      idata.data[idx++],
      idata.data[idx++],
      idata.data[idx++]
    );
    return d;
  }

  function rgbDistance(p1, p2) {
    return Math.sqrt(
      Math.pow(p1[0] - p2[0], 2) +
        Math.pow(p1[1] - p2[1], 2) +
        Math.pow(p1[2] - p2[2], 2)
    );
  }

  function rgbMean(pTab) {
    var m = [0, 0, 0];

    for (var i = 0; i < pTab.length; i++) {
      m[0] += pTab[i][0];
      m[1] += pTab[i][1];
      m[2] += pTab[i][2];
    }

    m[0] /= pTab.length;
    m[1] /= pTab.length;
    m[2] /= pTab.length;

    return m;
  }

  function backgroundMask(idata, threshold) {
    var rgbv_no = pixelAt(idata, 0, 0);
    var rgbv_ne = pixelAt(idata, idata.width - 1, 0);
    var rgbv_so = pixelAt(idata, 0, idata.height - 1);
    var rgbv_se = pixelAt(idata, idata.width - 1, idata.height - 1);

    var thres = threshold || 10;
    if (
      rgbDistance(rgbv_no, rgbv_ne) < thres &&
      rgbDistance(rgbv_ne, rgbv_se) < thres &&
      rgbDistance(rgbv_se, rgbv_so) < thres &&
      rgbDistance(rgbv_so, rgbv_no) < thres
    ) {
      // Mean color
      var mean = rgbMean([rgbv_ne, rgbv_no, rgbv_se, rgbv_so]);

      // Mask based on color distance
      var mask = [];
      for (var i = 0; i < idata.width * idata.height; i++) {
        var d = rgbDistance(mean, [
          idata.data[i * 4],
          idata.data[i * 4 + 1],
          idata.data[i * 4 + 2]
        ]);
        mask[i] = d < thres ? 0 : 255;
      }

      return mask;
    }
  }

  function applyMask(idata, mask) {
    for (var i = 0; i < idata.width * idata.height; i++) {
      idata.data[4 * i + 3] = mask[i];
    }
  }

  function erodeMask(mask, sw, sh) {
    var weights = [1, 1, 1, 1, 0, 1, 1, 1, 1];
    var side = Math.round(Math.sqrt(weights.length));
    var halfSide = Math.floor(side / 2);

    var maskResult = [];
    for (var y = 0; y < sh; y++) {
      for (var x = 0; x < sw; x++) {
        var so = y * sw + x;
        var a = 0;
        for (var cy = 0; cy < side; cy++) {
          for (var cx = 0; cx < side; cx++) {
            var scy = y + cy - halfSide;
            var scx = x + cx - halfSide;

            if (scy >= 0 && scy < sh && scx >= 0 && scx < sw) {
              var srcOff = scy * sw + scx;
              var wt = weights[cy * side + cx];

              a += mask[srcOff] * wt;
            }
          }
        }

        maskResult[so] = a === 255 * 8 ? 255 : 0;
      }
    }

    return maskResult;
  }

  function dilateMask(mask, sw, sh) {
    var weights = [1, 1, 1, 1, 1, 1, 1, 1, 1];
    var side = Math.round(Math.sqrt(weights.length));
    var halfSide = Math.floor(side / 2);

    var maskResult = [];
    for (var y = 0; y < sh; y++) {
      for (var x = 0; x < sw; x++) {
        var so = y * sw + x;
        var a = 0;
        for (var cy = 0; cy < side; cy++) {
          for (var cx = 0; cx < side; cx++) {
            var scy = y + cy - halfSide;
            var scx = x + cx - halfSide;

            if (scy >= 0 && scy < sh && scx >= 0 && scx < sw) {
              var srcOff = scy * sw + scx;
              var wt = weights[cy * side + cx];

              a += mask[srcOff] * wt;
            }
          }
        }

        maskResult[so] = a >= 255 * 4 ? 255 : 0;
      }
    }

    return maskResult;
  }

  function smoothEdgeMask(mask, sw, sh) {
    var weights = [
      1 / 9,
      1 / 9,
      1 / 9,
      1 / 9,
      1 / 9,
      1 / 9,
      1 / 9,
      1 / 9,
      1 / 9
    ];
    var side = Math.round(Math.sqrt(weights.length));
    var halfSide = Math.floor(side / 2);

    var maskResult = [];
    for (var y = 0; y < sh; y++) {
      for (var x = 0; x < sw; x++) {
        var so = y * sw + x;
        var a = 0;
        for (var cy = 0; cy < side; cy++) {
          for (var cx = 0; cx < side; cx++) {
            var scy = y + cy - halfSide;
            var scx = x + cx - halfSide;

            if (scy >= 0 && scy < sh && scx >= 0 && scx < sw) {
              var srcOff = scy * sw + scx;
              var wt = weights[cy * side + cx];

              a += mask[srcOff] * wt;
            }
          }
        }

        maskResult[so] = a;
      }
    }

    return maskResult;
  }

  /**
   * Mask Filter
   * @function
   * @name Mask
   * @memberof Konva.Filters
   * @param {Object} imageData
   * @example
   * node.cache();
   * node.filters([Konva.Filters.Mask]);
   * node.threshold(200);
   */
  Konva.Filters.Mask = function(imageData) {
    // Detect pixels close to the background color
    var threshold = this.threshold(),
      mask = backgroundMask(imageData, threshold);
    if (mask) {
      // Erode
      mask = erodeMask(mask, imageData.width, imageData.height);

      // Dilate
      mask = dilateMask(mask, imageData.width, imageData.height);

      // Gradient
      mask = smoothEdgeMask(mask, imageData.width, imageData.height);

      // Apply mask
      applyMask(imageData, mask);

      // todo : Update hit region function according to mask
    }

    return imageData;
  };

  Konva.Factory.addGetterSetter(
    Konva.Node,
    'threshold',
    0,
    Konva.Validators.getNumberValidator(),
    Konva.Factory.afterSetFilter
  );
})();